It is a large ceiling and I've made an opacity map and applied it for the cutouts. The problem is if I use the opacity map the box basically becomes two planes and you can see the middle as if it were empty and thus not get the feel as if they were cut out from a block of a panel. On the other hand if I create line work extrude those and subtract them from all the ceiling panels I think it would be a very inefficient way of modeling with all those surfaces and tax my computer resources.

Any recommended ways of achieving the desired result besides the ones I already mentioned?